Checking for border width > 0 before setting the border style to NS_STYLE_BORDER_STYLE_BG_INSET.

This fixes a bug where style changes were causing table cell borders to appear when previously there
were none. b=25425 r=karnaze

content/html/content/src/nsHTMLTableElement.cpp

@@ -1087,7 +1087,7 @@ MapAttributesInto(const nsIHTMLMappedAttributes* aAttributes,
     if (readDisplay && (readDisplay->mDisplay == NS_STYLE_DISPLAY_TABLE_CELL)) {
       // set the cell's border from the table
       aAttributes->GetAttribute(nsHTMLAtoms::border, value);
-      if ((value.GetUnit() == eHTMLUnit_Pixel) ||
+      if (((value.GetUnit() == eHTMLUnit_Pixel) && (value.GetPixelValue() > 0)) ||
           (value.GetUnit() == eHTMLUnit_Empty)) {
         float p2t;
         aPresContext->GetPixelsToTwips(&p2t);

layout/html/content/src/nsHTMLTableElement.cpp

@@ -1087,7 +1087,7 @@ MapAttributesInto(const nsIHTMLMappedAttributes* aAttributes,
     if (readDisplay && (readDisplay->mDisplay == NS_STYLE_DISPLAY_TABLE_CELL)) {
       // set the cell's border from the table
       aAttributes->GetAttribute(nsHTMLAtoms::border, value);
-      if ((value.GetUnit() == eHTMLUnit_Pixel) ||
+      if (((value.GetUnit() == eHTMLUnit_Pixel) && (value.GetPixelValue() > 0)) ||
           (value.GetUnit() == eHTMLUnit_Empty)) {
         float p2t;
         aPresContext->GetPixelsToTwips(&p2t);